The present invention relates generally to assemblies for the immersion of parameter determining devices into molten metal and more particularly, to a holder assembly having a section thereof which may be easily replaced if damaged.
During the refining of metal such as the refining of iron to steel and in the preparation of metals for casting, it is essential that certain parameters of the molten metal be accurately and swiftly determined. Some of these parameters are determined by immersing sensing devices into the molten metal that provide electrical signals that are indicative of the magnitude of the parameter. Such sensing devices are used to determine temperature by means of a thermocouple element, oxygen by means of an electrochemical cell, and carbon by means of temperature measurements made as an isolated sample cools through various thermal arrest temperatures. Other parameters of the molten metal require that a sample be removed from the bath of molten metal and be studied by chemical analysis or a metallographic analysis. Typical of such parameters are chemical composition and structure.
Parameter determining devices and particularly those to generate electrical signals while immersed in the molten metal are immersed in the molten metal by means of a holding assembly sometimes called a manipulator consisting of an iron pipe having electrical wires extending therethrough and terminating in an appropriate plug-in connector structure at its distal end. During immersion, it is essential that the manipulator be physically and thermally protected from the molten metal in order to prevent damage to or destruction of the manipulator. This protection has commonly been provided by a paper tube formed as an integral part of an expendable parameter detecting device. Depending on the length of the manipulator, such paper tubes range in length from two feet to eight feet and surround the lower end of the manipulator thereby providing a protective sleeve. The cost of the manipulator has been very high in comparison to the cost of the expendable parameter determining element and the paper protective sleeve. Therefore, the economics of such practices dictate that manipulators survive a large number of measurements before being damaged or destroyed.
However, because of the hostile environment in which such manipulators are used, they are very often inadvertently prematurely damaged or destroyed, usually in the region of the manipulator near the molten metal. In the past, such destroyed or damaged manipulators have either been replaced or repaired, if possible, either of which practices have been quite costly to the user.